Manufacture of carburized silica



May 2, 1939. c. A. JAcoBsoN 2,156,591

MANUFACTURE OF CARBURIZED SILICA Filed June 29, 1956 T W 6 1/ Th: 7]

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25 GASES LIGHT 77 a W SEPAEA fi I 1 T0 FURNACE l 5 RUBBER W 4 .4 2.5 20 $2? M22 T'O6T/LL 4) T0 RECOVERY OF PHENOL, BE/vzoL, ETC. gum-Mon Carl d7. (JZLCO bson,

Patented May 2, 1939 STATES MANUFAGIURE F CARBURIZED SILICA Carl Alfred Jacobson, Morgantown, W.'Va., assignor to Scalco By-Products Company, Bluefieid, W. Va, a corporation of West Virginia Application June 29,

invention relates to manufacture of carburized silica; and it comprises a process wherein a tar of the nature of coal tar is intimately mixed with a finely divided siliceous product of the t nature of diatomaceous earth, said mixture is passed continuously through a reaction zone! wherein it is subjected to a destructive distillation and the resulting solid product is "continuously withdrawn; the vapors formed in the process are to partially condensed, the condensate being subjected to a fractional distillation for the recovery of various products, the remaining vapors are scrubbed with a light oil to remove other valuable products and the remaining gases are then recovw cred; all as more fully hereinafter set forth and as claimed.

It has hitherto been proposed to prepare a carburized silica product by submitting to destructive distillation a mixture of a carbonaceous as substance, such as coal, and a siliceous substance,

such as diatomaceous earth. Such a process is described in my prior U. S. Patent No. 1,940,352. I have called this product Silica Blac When employing a carbonaceous material such as coal, however, a. larger amount of ash is carried along with the silica black products which tends to dis-' color the same and to give a product of varying for the recovery of all the valuable distillates as by-products of the process. I have also improved my prior process by the development of a continuous method which produces a better product with a substantial reduction in over-all cost.

I have made the further discovery that when coal tar is destructively distilled with diatoms.- ceous, earth or other siliceous material of like nature the latter acts as a catalyst and the coal tar is catalytically decomposed. This catalytic decomposition of the coal tar results in the production of increased amounts of phenol, cresol and mixed hydrocarbons and nearly twice. the

. normal amounts of naphthalenepanthracene and phenanthrene. In addition to these products,

there is produced some anthraquinone which, I

have found, can be separated easily. This lastas mentioned product is not obtained in the ordinary 1936, Serial No. 88,021

distillation of coal tar but is generated, presumably, by the catalytic oxidation of anthracene in my process. Furthermore, large volumes of a rich combustible gas are obtained which may be utilized in this or other arts.

Broadly stated the present invention contemplates the continuous destructive distillation of coal or other tar of like nature in intimate admixture with flnely divided diatomaceous earth, or other siliceous material of like nature, such as iniusorial earth, in such manner that there is obtained a carburized silica of greatly improved texture, coloring power, etc.,.along with the products oi the destructive distillation of tar.

In order that my process may be explained in greater detail reference is made to the accompanying drawing which shows, more or less diagrammatically, an advantageous form of apparatus for carrying out my said process. In this showing: v

Fig. 1 is a front elevation of my retort with the furnace in section,

Fig. 2 is a section along the lines 22 of Fig. 1, while Fig. 3 is a diagrammatic showing of one method of treating the volatile products obtained in my process.

In my process, wherein use is made of the apparatus shown in Figs. 1 and 2 an intimate mixture is first made of coal tar and finely divided diatomaceous earth or other siliceous substance, preferably in the ratio of about parts of tar to parts of diatomaceous earth, by weight. Mixing may be accomplished, for example, in a device (not shown) wherein a weighed amount of molten tar is poured or sprayed upon an agitated weighed mass of diatomaceous earth, taking care to maintain the mixture in a powdered state during mixing.

The powdered mixture of tar and siliceous material is conveyed to the hopper I from which it is allowed to fall into the long, vertically disposed retort pipes 2, 2', of which there may be any desired number and which are constructed of any suitable heat resistant alloy. These pipes pass through the furnace, generally designated at 3. The furnace is maintained at substantially an orange red to yellow heat (700 to 1200 C.) by .combustion of any suitable fuel fed through door d, the hot gases passing upwardly and around retort pipes 2, 2' and then through conduit 5 and flue 5. When solid fuel is used in the furnace the latter is provided with a grate 7 and ash pit 8. It is, of course, understood that I contemplate the use of any suitable fuel, solid, liquid or gaseous.

As a matter of fact, the fuel gas by-product of my process, may be utilized for this purpose, if desired.

The retort pipes 2, 2 are supported by flanges 9, 0' in the lower layer of the furnace and also by flanges I 0, l0 mounted in the base of the hopper I. In order to prevent clogging of the mixture passing through the retort pipes, their cross section may be increased slightly downwardly, the diameter at the bottom being of the order of two inches larger than that at the top.

In passing through the retort pipes 2, 2' the tar of the mixture is catalytically decomposed and destructively distilled at the temperature maintained in the furnace, all of the volatile products being allowed to pass out of the retort pipes into condenser pipes Ii, II and l2, l2. These condenser pipes, arranged on either side of the furnace, terminate in common conduits i3, I 3', respectively, which in turn may lead to a condenser It then to a separatory chamber l'l (Fig. 3) of suitable size and shape for the collection of the liquid distillate.

The rate of flow or drop of the distilling mixture in the retort pipes 2, 2' is regulated by the speed of the screw conveyor I. located in discharge pipe I! and driven by any suitable driving mechanism operating upon pulley 16.

The discharge pipe II, which is welded to the lower ends of retort pipes 2, 2' is slightly elevated at the exit end in order to prevent air from reaching the hot carburized silica before it has had time to cool. I have found this precaution desirable because the carbon will burn out and ruin the product if exposed to air at temperatures in excess of about 450 C. It is possible, of course,

to positively cool conveyor pipe i5. Or, if desired, a heat recuperator may be placed around the exit of conveyor I5 and employed for heating the air which is subsequently used for combustion purposes.

The volatile products obtained in my process, which pass from the retorts 2, 2' by means of pipes l2, l3 may be treated in various ways. The vapor pipes I3, it may be water cooled, if desired, as shown at l8 in Fig. 3, before passing to separator II. The gases leaving separator I! by pipe 28 are advantageously passed through a pump 19 which produces a slightly sub-atmospheric pressure in a small section of the retort tubes 2, 2'. This reduced pressure prevents loss of volatiles from hopper I. The gases leaving pump l9 are passed through a scrubber 20whichis fed by a light oil through line 2|. The scrubbed gases then pass into fuel gas receiver "by line 28. These gases may then leave by line 24 to be used in heating the furnace 3. I have found that my process, conducted as described, roughly yields from about 4500 to 5500 cubic feet of rich fuel gas-for each ton of tar processed.

The separator I1 is usually maintained at a temperature'ranging from about 20 to 50 C. The liquid products collecting in this separator are drawnoif by pipe 25. These products may be fractionated by conventional methods. The first fraction recovered, which is usually taken of! when the temperature reaches about C. contains a large amount of water and a light oil.

The oil can be readily separated and may be used to make a paint, as described subsequently. The aqueous solution remaining is alkaline and contains ammonia, pyridine and other basic constituents, which may be recovered by standard methods. r

The second fraction, usually taken off at tem- 'peratures ranging from about to 225 C.,-is

found to contain naphthalene, cresylic acid and phenol. These products can be separated and recovered by conventional methods. The third fraction, usually taken off at temperatures ranging from 225 to 300 C. contains anthracene oil from which crude anthracene can be separated on standing.

The fourth fraction taken off at temperatures ranging from about 300 to 400 C. is a greenish solid product dispersed in a heavy hydrocarbon oil. If this solid product is extracted with hot alcohol and the solution filtered it will be found that the filtrate contains anthracene while crude anthraqulnone is retained on the filter A small amount of phenanthrene is also present in this fraction and can be recovered if desired.

A fifth fraction may be recovered if desired at temperatures ranging from about 400 to 500 0., this fraction being a mixture of high molecular weight hydrocarbons in liquid form. Unless the temperature has gone to carbonization, a pitch remains in the retort which may be dissolved in the light oils obtained in the first fractions. This solution, to which silica black is added makes a superior paint, that is not only waterproof and rust resistant but withstands unusually high temperatures. For dissolving the pitch, benzol or other light oils may be used.

Before the above described fractionation of the distillate from I1 is undertaken, it may be desirable to first carry out a steam distillation of it, in which case the water layer wfll contain ammonia. pyridine, some phenol and other basic constituents. A fractionation of the oil layer will result in products very similar to those described above.

The scrubbing oil drawn off from the bottom of scrubber 20 by pipe 28 contains benzol, etc., which may be recovered by conventional methods, the oil used as a scrubbing liquid being then returned to the process. The light oil obtained in the first fraction, as described above, may be used as scrubbing liquid in the scrubber 20, if desired. It is advantageous to employ an oil from which the.

of fiow in the tubes varies directly with the temperature to which the tubes are heated. At very low rates of flow the furnace temperature may drop two to three hundred degrees, for example. The time of heating may vary from about 10 to 60 minutes.

After cooling, the silica black resulting from my process is preferably classified into at least two portions by air flotation in a manner illustrated in my prior acknowledged patent. The lighter portion may serve as an excellent black pigment, as a body for an acid proof or rustproof paint, an insecticide carrier or as a carrier for catalysts, while the heavier portion is found to be particularly useful as an absorbent for gases, as a filtering medium'and as a filler or pigment for hydraulic and other cements.

The finished products are comparatively soft powders, jet black in color and unusually uniorm in texture. The analysis oi typical samples is as follows:

The apparent specific gravity 01,.the lighter grade is approximately 0.215 while that of theheavier grade is 0.409.

While I have described the most advantageous embodiment of my process, various modifications can be made therein without departing from the scope oi the present invention. All types of true tars can be. em-

ployed in my process, that is, tars of the nature or coal tar. ically in Fig. 3 can, of course, be varied widely-in order to recover the various valuable products produced in my process. If desired the liquid products collected in separator i'i may be steam distilled to recover low boiling fractions, followed by vacuum distillation to prevent destruction of the heavier oils which are obtained in the process. The proportions of tar used in my process may vary from about to 100 parts for 100 parts of siliceous material.

Other modifications which fall within the scope oi the following claims will be immediately evident to those skilled in the art.

what Iconsider to be i The process illustrated diagrammat- What I claim'is: l. A process for preparing a soft uniformly colored and textured carburised silica product which comprises intimately mixing coal tar with finely divided diatomaceous earth in the proportions of from about 50 to 100 parts of tar to 100 partsoi diatomaceous earth, passing the mixture continuously through a reaction zone in the absence of air while controlling the temperature and time of passage through said reaction zone in such manner as to destructively distill the coal tar while carbonizlng the residual tar, recovering condensates from the volatiles derived irom said.

process and also recovering the carburized silica product.

2. The process oiclaim 1 wherein the mixture in the reaction zone is heated within the temperature range of from about 450 to 900 C.-

3. The process'of claim 1 wherein the coal tar" and diatomaceous earth are mixed in the proportions of about parts of tar to parts of diatomaceous earth.

4. The process of claim 1 wherein said volatiles are partially condensed and the remaining vapors are scrubbed with a light oil.

5. The process of claim 1 wherein said mixture is passed. in a body downw dly through said reaction zone by gravity, the resulting solid carburized silica product being continuously removed at the bottom of said reaction zone andsaid mixture being added at the top of said zone to maintain a body of reacting material in said zone.

CARI-l ALFRED JACOBSON. 

